Add LGTM code quality badges

[xcorail]

Hi there!

I thought you might be interested in adding these code quality badges to your project. They will indicate a very high code quality to potential users and contributors.
You can also check the alerts discovered by LGTM.

N.B.: I am on the team behind LGTM.com, I'd appreciate your feedback on this initiative, whether you're interested or not, if you find time to drop me a line. Thanks.

[cwhanse]

@wholmgren some interesting bugs found by the LGTM alerts

[wholmgren]

Looks like it could be useful.

So far as I can tell, a few of the reported errors are incorrect. These include:

• NotImplementedType errors in singlediode.py are probably hit due to the optional dependency allowance. see here
• If I correctly understand thepvsystem.py method signature complaint (SingleAxisTracker.get_aoi signature differs from PVSystem.get_aoi signature) then it's not a problem. see here

The imports should be cleaned up, though they are not hurting anything. Same for unused and identically assigned variables.

This forecast.py report is a bug.

We'd probably want to add a .lgtm.yml file similar to metpy

Most importantly we'd want to enable github integration to check pull requests. This is much more interesting to me than badges in the readme.

[mikofski]

NotImplementedType errors in singlediode.py are probably hit due to the optional dependency allowance.

Actually, I think it is a bug. I should have used brentq = lambda: NotImplemented so that it's callable because NotImplemented is a constant, and will raise an exception if called:

TypeError: 'NotImplementedType' object is not callable

Or NotImplementedError could also work better because it's a callable.

Sorry, I can send a pr to address it. Shall I open a ticket, or just wait until the SciPy dependency discussion is resolved?

[xcorail]

Hi @cwhanse @wholmgren

Happy of this feedback, and thanks a lot for the detailed report. Allow me to pass it to my python colleagues so that they can check the false positives.

Most importantly we'd want to enable github integration to check pull requests. This is much more interesting to me than badges in the readme.

I cannot agree more. PR integration is indeed the usage we recommend. I think the badges are more interesting for your potential users. Activating PR integration is a one-click operation.

[wholmgren]

@mikofski thanks for checking! please do put in a quick pr.

[wholmgren]

Added PR integration. Easy to remove if we don't like it.

Edited to add that I've turned off the auto-comment feature. I think the report in the Github integrations box is sufficient.

[wholmgren]

I'll go ahead and merge this and separately add a .lgtm.yml file. Thanks for the push, @xcorail.